Oil supply system for fluid film damper

ABSTRACT

A fluid film damper may comprise a sleeve, an annular support housing surrounding the sleeve, an annular volume between the annular support housing and the sleeve, a first supply conduit in fluid communication with a first inlet to the annular volume, a second supply conduit in fluid communication with a second inlet to the annular volume, wherein the first inlet is disposed opposite the annular volume from the second inlet, and a common oil supply conduit in fluid communication with the annular volume via a check valve, wherein the common oil supply conduit supplies the fluid to the annular volume via the first supply conduit and the second supply conduit.

FIELD

The present disclosure relates to gas turbine engines, and, morespecifically, to fluid film dampers for damping cyclical, transverseorbital movement of a gas turbine engine rotor.

BACKGROUND

Oil is typically supplied to a bearing damper to reduce the oscillationamplitude of an unbalanced engine rotor (e.g. bowed rotor during enginestart). As the unbalanced engine rotor rotates, an oil pressureoscillation may be induced in the bearing damper oil supply line. Acheck valve in the bearing damper oil supply line may be provided toprevent the large amplitude oil pressure oscillation from working itsway upstream of the check valve. However, depending upon the design anddynamic response of the check valve, a large amplitude oil pressureoscillation may still work its way upstream of the check valve.

SUMMARY

A fluid film damper is disclosed, comprising a sleeve, an annularsupport housing surrounding the sleeve, an annular volume between theannular support housing and the sleeve, a first supply conduit in fluidcommunication with a first inlet to the annular volume, a second supplyconduit in fluid communication with a second inlet to the annularvolume, wherein the first inlet is disposed opposite the annular volumefrom the second inlet, and a common oil supply conduit in fluidcommunication with the annular volume via a check valve, wherein thecommon oil supply conduit supplies the fluid to the annular volume viathe first supply conduit and the second supply conduit.

In various embodiments, the first inlet is disposed 180° around theannular volume from the second inlet.

In various embodiments, the sleeve is mounted about a shaft beingsupported by bearings.

In various embodiments, the shaft rotates about a central shaft axiswith respect to the sleeve.

In various embodiments, the fluid film damper dampens the transverseorbital movement of a vibration excited from the shaft whereby a highpressure and low pressure wave pattern precesses orbitally within saidannular volume to drive the fluid between the first inlet and the secondinlet via the first supply conduit and the second supply conduit.

In various embodiments, the check valve prevents back flow for the fluidfrom the first supply conduit and from the second supply conduit.

In various embodiments, the check valve is coupled halfway between thefirst inlet and the second inlet.

A fluid film damper is disclosed, comprising a sleeve, an annularsupport housing surrounding the sleeve, an annular volume between theannular support housing and the sleeve, a first supply conduit in fluidcommunication with a first inlet to the annular volume, a second supplyconduit in fluid communication with a second inlet to the annularvolume, wherein the first inlet is disposed opposite the annular volumefrom the second inlet, and the first supply conduit and the secondsupply conduit form a full loop flow path between the first inlet andthe second inlet, a common oil supply conduit in fluid communicationwith the annular volume via the first supply conduit and the secondsupply conduit, and a check valve, wherein the common oil supply conduitsupplies the fluid to the first supply conduit and the second supplyconduit via the check valve.

In various embodiments, the first inlet is disposed 180° around theannular volume from the second inlet.

In various embodiments, the sleeve is mounted about a shaft beingsupported by bearings.

In various embodiments, the shaft rotates about a central shaft axiswith respect to the sleeve.

In various embodiments, fluid film damper controls the transverseorbital movement of a vibration excited from the shaft whereby a highpressure and low pressure wave pattern precesses orbitally within saidannular volume to drive the fluid between the first inlet and the secondinlet via the first supply conduit and the second supply conduit.

In various embodiments, the check valve prevents back flow for the fluidfrom the first supply conduit and from the second supply conduit.

In various embodiments, the check valve is coupled halfway between thefirst inlet and the second inlet.

In various embodiments, a first length of a first flow path between thecheck valve and the first inlet is equal to a second length of a secondflow path between the check valve and the second inlet.

A method for installing a fluid film damper is disclosed, comprisingcoupling a first supply conduit to a first inlet to an annular volume,coupling a second supply conduit to a second inlet to the annularvolume, wherein the first inlet is disposed opposite the annular volumefrom the second inlet, coupling a check valve to the first supplyconduit and the second supply conduit, and coupling a common oil supplyconduit to the check valve, wherein the common oil supply conduit is influid communication with the annular volume via the check valve, whereinthe common oil supply conduit supplies the fluid to the annular volumevia the first supply conduit and the second supply conduit.

In various embodiments, the first supply conduit is coupled to thesecond supply conduit to form a full loop flow path between the firstinlet and the second inlet.

In various embodiments, the method further comprises disposing anannular support housing to surround a sleeve.

In various embodiments, the annular volume is at least partially definedby the annular support housing and the sleeve.

In various embodiments, the first inlet is disposed 180° around theannular volume from the second inlet.

The foregoing features and elements may be combined in variouscombinations without exclusivity, unless expressly indicated hereinotherwise. These features and elements as well as the operation of thedisclosed embodiments will become more apparent in light of thefollowing description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present disclosure is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present disclosure, however, may bestbe obtained by referring to the detailed description and claims whenconsidered in connection with the figures, wherein like numerals denotelike elements.

FIG. 1 illustrates a schematic view of a gas turbine engine, inaccordance with various embodiments;

FIG. 2A is an improved damper schematically illustrated in a firstorbital position showing inlet supply lines, in accordance with variousembodiments;

FIG. 2B is an improved damper schematically illustrated in a secondorbital position showing inlet supply lines, in accordance with variousembodiments;

FIG. 3 illustrates a longitudinal cross sectional view of a damper witha schematic view of an oil supply system coupled to the damper, inaccordance with various embodiments;

FIG. 4 is a method for installing a fluid film damper, in accordancewith various embodiments; and

FIG. 5 illustrates a schematic view of a damper fluid supply arrangementwith a first supply conduit and a second supply conduit formed into asupport housing, in accordance with various embodiments;

DETAILED DESCRIPTION

The detailed description of various embodiments herein makes referenceto the accompanying drawings, which show various embodiments by way ofillustration. While these various embodiments are described insufficient detail to enable those skilled in the art to practice thedisclosure, it should be understood that other embodiments may berealized and that logical, chemical, and mechanical changes may be madewithout departing from the spirit and scope of the disclosure. Thus, thedetailed description herein is presented for purposes of illustrationonly and not of limitation. For example, the steps recited in any of themethod or process descriptions may be executed in any order and are notnecessarily limited to the order presented. Furthermore, any referenceto singular includes plural embodiments, and any reference to more thanone component or step may include a singular embodiment or step. Also,any reference to attached, fixed, connected, or the like may includepermanent, removable, temporary, partial, full, and/or any otherpossible attachment option. Surface shading lines may be used throughoutthe figures to denote different parts but not necessarily to denote thesame or different materials. In some cases, reference coordinates may bespecific to each figure.

As used herein, “aft” refers to the direction associated with theexhaust (e.g., the back end) of a gas turbine engine. As used herein,“forward” refers to the direction associated with the intake (e.g., thefront end) of a gas turbine engine. A first component that is “radiallyoutward” of a second component means that the first component ispositioned at a greater distance away from the engine centrallongitudinal axis than the second component. A first component that is“radially inward” of a second component means that the first componentis positioned closer to the engine central longitudinal axis than thesecond component. In the case of components that rotatecircumferentially about the engine central longitudinal axis, a firstcomponent that is radially inward of a second component rotates througha circumferentially shorter path than the second component. Theterminology “radially outward” and “radially inward” may also be usedrelative to references other than the engine central longitudinal axis.For example, a first component of a combustor that is radially inward orradially outward of a second component of a combustor is positionedrelative to the central longitudinal axis of the combustor. The term“axial,” as used herein, refers to a direction along or parallel to theengine central longitudinal axis.

A fluid film damper system as disclosed herein may comprise a common oilsupply conduit split into two equal length supply conduits in fluidcommunication with an annular volume. The supply conduits may provide anopen flow path between two opposite sides of the annular volume. Thefluid film damper system may reduce hydraulic pressure experienced by acheck valve in the common oil supply conduit. Stated differently, thefluid film damper system may attenuate the amplitude of the oil pressureoscillation at the check valve and upstream of the check valve. In thisregard, a fluid film damper system as disclosed herein may improve theservice life of the check valve, the supply conduits, and other oilsystem components located upstream of the check valve. Furthermore, animbalance in oil pressure between a first inlet of the fluid film damperand a second inlet of the fluid film damper may result in some oil flowfrom the high pressure inlet to the low pressure inlet. This oil flowmay reduce cavitation in the low pressure side, improving bearing and/ordamper component life.

In various embodiments and with reference to FIG. 1, a gas turbineengine 20 is provided. Gas turbine engine 20 may be a two-spool turbofanthat generally incorporates a fan section 22, a compressor section 24, acombustor section 26 and a turbine section 28. Alternative engines mayinclude, for example, an augmentor section among other systems orfeatures. In operation, fan section 22 can drive coolant (e.g., air)along a bypass flow-path B while compressor section 24 can drive airalong a core flow-path C for compression and communication intocombustor section 26 then expansion through turbine section 28. Althoughdepicted as a turbofan gas turbine engine 20 herein, it should beunderstood that the concepts described herein are not limited to usewith turbofans as the teachings may be applied to other types of turbineengines. Further, three-spool architectures may also be included.

Gas turbine engine 20 may generally comprise a low speed spool 30 and ahigh speed spool 32 mounted for rotation about an engine centrallongitudinal axis A-A′ relative to an engine static structure 36 orengine case via several bearing systems 38, 38-1, and 38-2. Enginecentral longitudinal axis A-A′ is oriented in the z direction on theprovided xyz axis. It should be understood that various bearing systems38 at various locations may alternatively or additionally be provided,including for example, bearing system 38, bearing system 38-1, andbearing system 38-2.

Low speed spool 30 may generally comprise an inner shaft 40 thatinterconnects a low pressure compressor 44 and a low pressure turbine46. Inner shaft 40 may be connected to fan 42 through a gearedarchitecture 48 that can drive fan 42 at a lower speed than low speedspool 30. Geared architecture 48 may comprise a gear assembly 60enclosed within a gear housing 62. Gear assembly 60 couples inner shaft40 to a rotating fan structure. High speed spool 32 may comprise anouter shaft 50 that interconnects a high pressure compressor 52 and highpressure turbine 54.

A combustor 56 may be located between high pressure compressor 52 andhigh pressure turbine 54. The combustor section 26 may have an annularwall assembly having inner and outer shells that support respectiveinner and outer heat shielding liners. The heat shield liners mayinclude a plurality of combustor panels that collectively define theannular combustion chamber of the combustor 56. An annular coolingcavity is defined between the respective shells and combustor panels forsupplying cooling air. Impingement holes are located in the shell tosupply the cooling air from an outer air plenum and into the annularcooling cavity.

A mid-turbine frame 57 of engine static structure 36 may be locatedgenerally between high pressure turbine 54 and low pressure turbine 46.Mid-turbine frame 57 may support one or more bearing systems 38 inturbine section 28. Inner shaft 40 and outer shaft 50 may be concentricand rotate via bearing systems 38 about the engine central longitudinalaxis A-A′, which is collinear with their longitudinal axes. As usedherein, a “high pressure” compressor or turbine experiences a higherpressure than a corresponding “low pressure” compressor or turbine.

The core airflow C may be compressed by low pressure compressor 44 thenhigh pressure compressor 52, mixed and burned with fuel in combustor 56,then expanded over high pressure turbine 54 and low pressure turbine 46.Turbines 46, 54 rotationally drive the respective low speed spool 30 andhigh speed spool 32 in response to the expansion.

In various embodiments, geared architecture 48 may be an epicyclicalgear train, such as a star gear system (sun gear in meshing engagementwith a plurality of star gears supported by a carrier and in meshingengagement with a ring gear) or other gear system. Geared architecture48 may have a gear reduction ratio of greater than about 2.3 and lowpressure turbine 46 may have a pressure ratio that is greater than aboutfive (5). In various embodiments, the bypass ratio of gas turbine engine20 is greater than about ten (10:1). In various embodiments, thediameter of fan 42 may be significantly larger than that of the lowpressure compressor 44, and the low pressure turbine 46 may have apressure ratio that is greater than about five (5:1). Low pressureturbine 46 pressure ratio may be measured prior to inlet of low pressureturbine 46 as related to the pressure at the outlet of low pressureturbine 46 prior to an exhaust nozzle. It should be understood, however,that the above parameters are exemplary of various embodiments of asuitable geared architecture engine and that the present disclosurecontemplates other gas turbine engines including direct drive turbofans.A gas turbine engine may comprise an industrial gas turbine (IGT) or ageared aircraft engine, such as a geared turbofan, or non-gearedaircraft engine, such as a turbofan, or may comprise any gas turbineengine as desired.

With reference to FIG. 2A and FIG. 2B, a fluid film damper system 200 isillustrated in accordance with various embodiments. XYZ axes areprovided for ease of illustration. In various embodiments, fluid filmdamper system 200 comprises a support housing 210 disposed about acylindrical internal member 212 which is subject to attempted cyclicalorbital motion 214. Support housing 210 may be an annular supporthousing. Cylindrical internal member 212 may be a nonrotating bearingsleeve, hereinafter referred to as the sleeve 212. A flow of dampingfluid is introduced into the annular volume 216 formed between the innersurface 218 of the support housing 210 and the outer nonrotating surface220 of the sleeve 212 via a supply conduit (also referred to herein as afirst supply conduit) 222 and supply conduit (also referred to herein asa second supply conduit) 224. Supply conduit 222 and supply conduit 224may receive oil from a common oil supply conduit 240. Common oil supplyconduit 240 may comprise a check valve 242 to prevent back flow fromannular volume 216 to common oil supply conduit 240.

The fluid may fill the annular volume 216. During operation, the damperthus described absorbs the momentum of the sleeve 212 through viscousand hydro-dynamically created forces resulting from the presence of thedamping fluid in the annular volume 216.

The orbital motion 214 of the sleeve 212 causes a circumferentialpressure wave to be propagated around the inner surface 218 in advanceof the orbiting line of closest approach 226 between the sleeve 212 andthe support housing 210. The local fluid pressure reaches a maximumwithin the circumferential pressure wave which when resolved intocomponent forces produces a spring force, thereby exerting a substantialradial opposing force on the sleeve 212 and preventing undesirablecontact between the sleeve 212 and inner surface 218 and a damping forcewhich opposes the orbiting motion. For example, FIG. 2A illustratessleeve 212 at a first position of its orbit and FIG. 2B illustratessleeve 212 at a second position of its orbit.

Fluid pressure may be maintained within the annular volume 216 byproviding check valve 242. In various embodiments, supply conduit 222and supply conduit 224 may be sized to regulate the volume flow ofdamping fluid through the supply conduits 222, 224, as well as tomaintain the fluid pressure within the annular volume 216 as high aspracticable to prevent separation of dissolved air in the moving lowpressure zone. For typical aircraft gas turbine engines having alubricating oil supply average pressure of 30-200 pounds per square inch(207-1,380 kPa), the dynamic operating pressures of the annular volume216 may be in the range of 500 to 2.000 pounds per square inch (3.450 to13,800 kPa).

In various embodiments, supply conduit 222 supplies oil to a first inlet223 to annular volume 216 and supply conduit 224 supplies oil to asecond inlet 225 to annular volume 216. First inlet 223 is disposedopposite the annular volume 216 from second inlet 225. First inlet 223may be disposed one hundred and eighty degrees (180°) around the annularvolume 216 from second inlet 225. As the circumferential pressure wavepropagates around the annular volume 216, the pressure acting at supplyconduit 222 attempts to oscillate, similar to that of a sin wave. Thepressure acting at supply conduit 224 attempts to oscillate, similar tothat of a sin wave, equal and opposite to the pressure acting at supplyconduit 222. With particular focus on FIG. 2A, as the pressure at supplyconduit 224 increases, oil and/or oil pressure may be communicated fromannular volume 216, into supply conduit 224, through supply conduit 222and back into annular volume 216 (see arrows 290). In this regard,annular volume 216, supply conduit 222, and supply conduit 224 maydefine a full loop flow path 280. Full loop flow path 280 may begenerally free of obstructions (e.g., a valve). Similarly, withparticular focus on FIG. 2B, as the pressure at supply conduit 222increases, oil and/or oil pressure may be communicated from annularvolume 216, into supply conduit 222, through supply conduit 224 and backinto annular volume 216 (see arrows 292). Thus, full loop flow path 280tends to minimize pressure fluctuations in supply conduit 222 and supplyconduit 224. With momentary focus on FIG. 2A, by coupling first inlet223 to second inlet 225 via first supply conduit 222 and second supplyconduit 224, the relatively high pressure at second inlet 225 iseffectively canceled by the relatively low pressure at first inlet 223.Similarly, with momentary focus on FIG. 2B, by coupling first inlet 223to second inlet 225 via first supply conduit 222 and second supplyconduit 224, the relatively low pressure at second inlet 225 iseffectively canceled by the relatively high pressure at first inlet 223In this regard, the full loop configuration of supply conduit 222 andsupply conduit 224 may tend to minimize the pressure experienced bycheck valve 242.

In various embodiments, supply conduit 222 and supply conduit 224 may besized such that the flow path length through supply conduit 222, betweencheck valve 242 and annular volume 216, is equal to the flow path lengththrough supply conduit 224, between check valve 242 and annular volume216. In this regard, check valve 242 may be coupled half way betweenfirst inlet 223 and second inlet 225. Stated differently, common oilsupply conduit 240 may be split into two equal length supply paths(i.e., supply conduit 222 and supply conduit 224) in fluid communicationwith annular volume 216. In this manner, the pressure fluctuations(e.g., spikes in pressure) experienced by check valve 242 may tend to beminimized.

In various embodiments, common oil supply conduit 240 is connected inseries with supply conduit 222 and supply conduit 224. In variousembodiments, supply conduit 222 and supply conduit 224 are coupled inparallel between common oil supply conduit 240 and annular volume 216.

With reference to FIG. 3, a sectional view of an example fluid damper300 taken in the plane of the central shaft axis is illustrated, inaccordance with various embodiments. Fluid damper 300 may be suppliedwith oil from fluid supply 302, comprising supply conduit 222, supplyconduit 224, common oil supply conduit 240 and check valve 242. Theannular volume 316 is shown between the cylinder surface 320 and theinner surface 318 of the support housing 310. Longitudinal flow ofdamping fluid from the annular volume 316 is prevented by longitudinalseals 344, 346. Longitudinal seals 344, 346 may be any suitable sealincluding elastomeric O-rings, among others. Cylindrical member 312 maybe a nonrotating bearing sleeve mounted over a bearing 338. Rotatingshaft 350 may be supported by bearing 338. The orbital motion 214 (seeFIG. 2A and FIG. 2B) may be excited by a vibration of shaft 350.

Supply conduit 222 may be coupled to support housing 310. First inlet323 may comprise a channel or orifice disposed through support housing310. Supply conduit 224 may be coupled to support housing 310. Secondinlet 325 may comprise a channel or orifice disposed through supporthousing 310. However, in various embodiments, supply conduit 222 andsupply conduit 224 may be integral to support housing 310, for exampleas described with respect to FIG. 5 herein.

With reference to FIG. 4, a method 400 for installing a fluid filmdamper is provided, in accordance with various embodiments. Method 400includes coupling a first supply conduit to a first inlet to an annularvolume (step 410). Method 400 includes coupling a second supply conduitto a second inlet to the annular volume (step 420). Method 400 includescoupling a check valve to the first supply conduit and the second supplyconduit (step 430). Method 400 includes coupling a common oil supplyconduit to the check valve (step 440).

With combined reference to FIG. 3 and FIG. 4. Step 410 may includecoupling first supply conduit 222 to first inlet 323 to annular volume316. Step 420 may include coupling second supply conduit 224 to secondinlet 325 to annular volume 316. Step 430 may include coupling checkvalve 242 to be in fluid communication with first supply conduit 222 andsecond supply conduit 224, whereby a fluid is supplied to first supplyconduit 222 and second supply conduit 224. Step 440 may include couplingcommon oil supply conduit 240 to check valve 242, whereby the fluid issupplied to first supply conduit 222 and second supply conduit 224 viacheck valve 242.

With reference to FIG. 5, a schematic view of a support housing 510taken in the plane orthogonal of the central shaft axis is illustrated,in accordance with various embodiments. In various embodiments, a supplyconduit 522, a supply conduit 524, a first inlet 523, and a second inlet525 may be formed into support housing 510. In various embodiments,supply conduit 522, supply conduit 524, first inlet 523, and secondinlet 525 may be similar to supply conduit 222, supply conduit 224,first inlet 323, and second inlet 325, respectively, as described inFIG. 3. By forming supply conduit 522 and supply conduit 524 as channelsdisposed in support housing 510, check valve 242 may be coupled tosupport housing 510 via a single common oil supply conduit 240 routedfrom the check valve 242 to the support housing 510, as opposed to twoseparate supply conduits (e.g., supply conduit 222 and supply conduit224) being routed therebetween. In this regard, supply conduit 522,supply conduit 524, first inlet 523, and second inlet 525 may comprisechannels formed into support housing 510. Supply conduit 522, supplyconduit 524, first inlet 523, and/or second inlet 525 may be formed intosupport housing 510 via any suitable manufacturing technique, such asdrilling, milling, or casting, among others.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the inventions. The scope of the inventions is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “various embodiments”, “oneembodiment”, “an embodiment”, “an example embodiment”, etc., indicatethat the embodiment described may include a particular feature,structure, or characteristic, but every embodiment may not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases are not necessarily referring to the same embodiment.Further, when a particular feature, structure, or characteristic isdescribed in connection with an embodiment, it is submitted that it iswithin the knowledge of one skilled in the art to affect such feature,structure, or characteristic in connection with other embodimentswhether or not explicitly described. After reading the description, itwill be apparent to one skilled in the relevant art(s) how to implementthe disclosure in alternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to invoke 35 U.S.C. 112(f),unless the element is expressly recited using the phrase “means for.” Asused herein, the terms “comprises”, “comprising”, or any other variationthereof, are intended to cover a non-exclusive inclusion, such that aprocess, method, article, or apparatus that comprises a list of elementsdoes not include only those elements but may include other elements notexpressly listed or inherent to such process, method, article, orapparatus.

What is claimed is:
 1. A fluid film damper, comprising: a sleeve; anannular support housing surrounding the sleeve; an annular volumebetween the annular support housing and the sleeve; a first supplyconduit in fluid communication with a first inlet to the annular volume;a second supply conduit in fluid communication with a second inlet tothe annular volume, wherein the first inlet is disposed opposite theannular volume from the second inlet; and a common oil supply conduit influid communication with the annular volume via a check valve, whereinthe common oil supply conduit supplies the fluid to the annular volumevia the first supply conduit and the second supply conduit.
 2. The fluidfilm damper of claim 1, wherein the first inlet is disposed 180° aroundthe annular volume from the second inlet.
 3. The fluid film damper ofclaim 1, wherein the sleeve is mounted about a shaft being supported bya bearing.
 4. The fluid film damper of claim 3, wherein the shaftrotates about a central shaft axis with respect to the sleeve.
 5. Thefluid film damper of claim 4, wherein the fluid film damper dampens thetransverse orbital movement of a vibration excited from the shaftwhereby a high pressure and low pressure wave pattern precessesorbitally within said annular volume to drive the fluid between thefirst inlet and the second inlet via the first supply conduit and thesecond supply conduit.
 6. The fluid film damper of claim 1, wherein thecheck valve prevents back flow for the fluid from the first supplyconduit and from the second supply conduit.
 7. The fluid film damper ofclaim 1, wherein the check valve is coupled halfway between the firstinlet and the second inlet.
 8. A fluid film damper, comprising: asleeve; an annular support housing surrounding the sleeve; an annularvolume between the annular support housing and the sleeve; a firstsupply conduit in fluid communication with a first inlet to the annularvolume; a second supply conduit in fluid communication with a secondinlet to the annular volume, wherein the first inlet is disposedopposite the annular volume from the second inlet, and the first supplyconduit and the second supply conduit form a full loop flow path betweenthe first inlet and the second inlet; a common oil supply conduit influid communication with the annular volume via the first supply conduitand the second supply conduit; and a check valve, wherein the common oilsupply conduit supplies the fluid to the first supply conduit and thesecond supply conduit via the check valve.
 9. The fluid film damper ofclaim 8, wherein the first inlet is disposed 180° around the annularvolume from the second inlet.
 10. The fluid film damper of claim 8,wherein the sleeve is mounted about a shaft being supported by abearing.
 11. The fluid film damper of claim 10, wherein the shaftrotates about a central shaft axis with respect to the sleeve.
 12. Thefluid film damper of claim 11, wherein fluid film damper controls thetransverse orbital movement of a vibration excited from the shaftwhereby a high pressure and low pressure wave pattern precessesorbitally within said annular volume to drive the fluid between thefirst inlet and the second inlet via the first supply conduit and thesecond supply conduit.
 13. The fluid film damper of claim 8, wherein thecheck valve prevents back flow for the fluid from the first supplyconduit and from the second supply conduit.
 14. The fluid film damper ofclaim 8, wherein the check valve is coupled halfway between the firstinlet and the second inlet.
 15. The fluid film damper of claim 8,wherein a first length of a first flow path between the check valve andthe first inlet is equal to a second length of a second flow pathbetween the check valve and the second inlet.
 16. A method forinstalling a fluid film damper, comprising: coupling a first supplyconduit to a first inlet to an annular volume; coupling a second supplyconduit to a second inlet to the annular volume, wherein the first inletis disposed opposite the annular volume from the second inlet; couplinga check valve to the first supply conduit and the second supply conduit;and coupling a common oil supply conduit to the check valve, wherein thecommon oil supply conduit is in fluid communication with the annularvolume via the check valve, wherein the common oil supply conduitsupplies the fluid to the annular volume via the first supply conduitand the second supply conduit.
 17. The method of claim 16, wherein thefirst supply conduit is coupled to the second supply conduit to form afull loop flow path between the first inlet and the second inlet. 18.The method of claim 16, further comprising disposing an annular supporthousing to surround a sleeve.
 19. The method of claim 18, wherein theannular volume is at least partially defined by the annular supporthousing and the sleeve.
 20. The method of claim 16, wherein the firstinlet is disposed 180° around the annular volume from the second inlet.